It is common practice in the construction industry to apply a wrap that is resistant to penetration by liquid water and air in the construction of the exterior walls and roofs of building structures. Such wraps are commonly referred to as housewraps or roofing underlayments. Typically, housewraps and roofing underlayments are also breathable, i.e. permeable to water vapor, to help prevent the buildup of moisture within the walls and roof of a building, which can cause mold and rot and be highly damaging to the structure, though some roofing underlayments are non-breathable.
It is known to apply drainage-promoting means to such construction wraps. For example, Ehrman et al., U.S. Pat. No. 7,607,270, discloses a wrap comprising a weather-resistant membrane and a series of spaced-apart, elongate filament spacers bonded to the membrane and having depressions providing drainage paths.
The present invention is direct to improvements in drainage-promoting wraps and to methods and apparatus making them.